Hobbing machine



July 18, 1967 BATORsKl ET AL 3,331,285

HOBBING MACHINE 3 Sheets-Sheet 1 Filed Oct. 18, 1965 Edward Q. i ficdov'sm Ruaaw P undk July 18, 1967 E. J. BATORSKI ET L 3,331,285

HOBBING MACHINE 3 Sheets-Sheet 2 Filed Oct. 18, 1965 INVENTOIE 4m m mu Bu \V.P h Z Wu R Dime A EORNE July 18, 1967 Filed can. 18, 1965 E. J. BATORSKI ET AL HOBBING MACHINE 3 Sheets-Sheet 3 PRESSURE REGULHTlNG VRLVE HUI 76 55 =L11LTJ INTENSWEK MAJ INVENTOR: Edward J. Emcovsfi Rudd? P. HuncH' United States Patent 3,331,285 HOBBING MACHINE Edward J. Batorski, Wallingford, and Rudolf P. Hundt, Cheshire, Conn., assiguors to Textron Inc., Providence, R.I., a corporation of Rhode Island Filed Oct. 18, 1965, Ser. No. 497,278 16 Claims. (Cl. 90-4) This invention relates to hobbing machines, and more particularly relates to a new and improved structure of a hobbing machine.

A hobbing machine generally comprises a base member with a main column extending vertically therefrom. The main column carries a hob head linearly movable thereon toward and away from the axis of a workpiece carried on a Worktable which is movable vertically on the column usually by means of a lead screw which raises and lowers the workta'ble. The Worktable is usually guidably mounted to the column at both horizontally and vertically spaced apart ways which guide movement of the Worktable with respect to the column. These ways are generally the type in which one way is a positioning means and the other way is a guide means. For example, one way may be dovetail and the other of rectangular cross section.

In operation of a hobbing machine, when the hob cuts into a workpiece, a large force is created. This cutting operation sets up a very large force which creates a moment on the Worktable which is restrained against such movement by the way guides. However, as much as there must be some clearance in the way guides the Worktable will not be essentially rigid with respect to the column, and some inaccuracies will be introduced into the gear or spline being cut by the hob. Additionally, the workpiece reacts against the force produced thereon by the hob, and will tend to produce a moment on the hob and its mounting device, usually referred to as a hob slide. To overcome this during a cutting operation the hob head and hob slide should be rigidly secured to the main column.

The present invention provides a new and improved hobbing machine wherein the workta-ble and hob slide are mounted to the main column in such a manner that these members are rigidly supported by the column and secured thereto. The invention further provides new and improved means for guidably mounting the Worktable to the column of the hobbing machine in such a way as to minimize the moment or torque acting upon the worktable and, further, to eliminate any clearance in the ways which position the Worktable on the main column. The invention further provides new and improved means for rigidly clamping the hob head through the hob slide directly to the main column. This is accomplished through the provision of new and improved ways having essentially zero clearance between the column and the worktable wherein the ways reside all in a common vertical plane. Additionally, new and improved clamping means are provided in association with the hob slides which rigidly clamp the hob slide and, therefore, the hob head carried directly to the main column. Such clamping means are efiective to produce a substantially uniformly distributed clamping force along the area of contact of the hob slide with the main column.

An object of this invention is to provide a new and improved hobbing machine construction.

Another object of this invention is to provide a construction for a hobbing machine including new and improved means for maintaining rigidity between the parts thereof during a hobbing operation.

Another object of this invention is to provide new and improved ways for movably positioning the Worktable of a hobbing machine on the supporting column thereof.

Another object of this invention is to provide a new 3,331,2b5 Patented July 18, 1967 and improved means for rigidly clamping the slide of a hobbing machine to the supporting column thereof during a hobbing operation.

A further object of this invention is to provide a new and improved hobbing machine in which the cooperating members are more rigidly positioned with respect to each other during a hobbing operation which increases the accuracy of the machine.

The features of the invention which are believed to be novel are pointed out with particularly and distinctly claimed in the concluding portion of this specification. However, the invention both as to its organization and operation, together with further objects and advantages thereof may best be appreciated by reference to the following detailed description taken in conjunction with the drawings, in which:

FIG. 1 is an elevation of a hobbing machine embodying the invention;

FIG. 2 is a view of the hobbing machine of FIG. 1 seen from the right side thereof, and partially cut away to facilitate illustration of features of the invention;

FIG. 3 is a plan view of the machine of FIGS. 1 and 2;

FIG. 4 is an enlarged view of the hob slide shown in FIG. 1, and partially cut away to facilitate illustration of the features thereof;

FIG. 5 is a view seen along the planes of line 55 of FIG. 4;

FIG. 6 is a view seen in the plane of lines 6-6 of FIG. 5; and

FIG. 7 is a schematic diagram of a hydraulic circuit which may be used in conjunction with the slide assembly of the disclosed apparatus.

A hobbing machine embodying the invention is generally indicated by the reference numeral 10 and comprises a base 11 supporting a rigid one-piece vertical column 12 of generally box shape. A hob slide 13 is horizontally movable on column 12 as hereinafter described. Slide 13 carries a hob head 14. Mounted to column 12 and base 11 is a Worktable 15 including a spindle driven chuck 16 adapted to hold a workpiece such as a gear, a shaft to be splined, or the like. Worktable 15 may be vertically reciprocated by means of a lead screw 17 driven through a gear 18 and pulley 19 from a motor 20. Worktable 15 includes a vertical column 21 which carries thereon ways 22 and 23 upon which a slide 24 having a footstock or tailstock 25 thereon is vertically reciprocal. It may thus be seen that a workpiece is adapted to be mounted in chuck 16, engaged by tailstock 25 and held in a position to be operated upon by hob head 14.

In accordance with the invention, the hobbing machine is made of extremely rigid construction and comprises only three major castings, which are the heavy cast base 11, a heavy single piece column 12 of generally box construction, and Worktable 15. As hereinafter described, new and improved means are provided for rigidizing the hob slide on column 12.

The Worktable is a single casting of box-like construction with the tailstock section and upper support structure extending from a plane paralleling the front of the column 12, as viewed in FIG. 1.

The workhead or Worktable 15 is supported for movement with respect to column 12 in a manner to provide increased rigidity therebetween and prevent any turning of the Worktable when the hob engages and operates upon a workpiece. It will be apparent that when the hob is cutting into a workpiece, the force of the hob and the reaction thereof will tend to move the Worktable counterclockwise (as viewed in FIG. 3) from the column 12. Where previously it had been the practice to mount the Worktable to the column on one rectangular and one dovetail way, and usually in two horizontally spaced apart planes, there was always some clearance in the ways. In

accordance with the present invention, new and improved means are provided for mounting the worktable to the column for vertical reciprocatory movement. Carried on column 12 by means of massive lugs or brackets are hardened and ground precision guide rods 28, 29 and 30. Guide rods 28 and 29 are of the same dimension and coaxial, and are in essence one interrupted guide rod. Rod 28 is supported at either end thereof by lugs or brackets 31 and 32, rigidly mounted to column 12. Guide rod 29 is similarly supported by lugs or brackets 33 and 34. The guide rods 28 and 29 are preferably shouldered at the ends thereof to be received in apertures therefor in the brackets 31-34. Guide 30 is similarly mounted to column 12 by means of brackets 35, 36 and 37. The guide rods are very rigidly held in fixed relation to column 12 and the axes of all rods 28, 29 and 30 reside in a common plane. Defined in worktable 15, and more particularly in massive lugs L defined integrally thereon, are accurately machined bores 39, 40, 41 and 42. Bores 39 and 40 are spaced apart vertically in worktable and are coaxial. Bores 41 and 42 are also coaxial. Disposed and mounted within bores 39, 40, 41 and 42 are precision reciprocating ball assemblies 43, 44, 45 and 46, respectively. In one form (not shown in detail) the reciprocating ball assemblies may comprise a plurality of generally elliptical races with the major axes thereof parallel to the axes of the guide rods. The lug walls defining the bores 39, 40, 41 and 42 are split or provided with an interruption as shown at 45 and 46 in FIG. 3, and threaded boxes are defined in the walls of lugs L transverse to such split or separation to receive tightening bolts 47 (FIGS. 1 and 3). By means of such tightening bolts 47, all of the walls defining bores 39, 40, 41 and 42 may be closed around their respective bearing assemblies to provide zero clearance between the bores, the bearing slides and the guide bars. With this construction, the worktable 15 is rigidly, but vertically, reciprocally mounted to column 12. Such mounting will prevent any turning of worktable 15 with respect to the base 11 or column 12 of the hobbing machine.

It will be further noted that all points of connection between the worktable and the column reside in a common vertical plane which includes the axes of rods 28, 29 and 30, and the axes of the rod-receiving bores and ball assemblies. With such a mode of connection, that is, the common points being in a single vertical plane, there will be no unbalance of moments tending to cock the work carriage on the column. It may further be noted that the footstock slide 24 is mounted to worktable 15 in a plane which resides between the axes of rods 28, 29 and 30.

Further, in accordance with the invention means are provided for rigidly clamping the hob slide and hob head to column 12 during operation thereof. As more clearly shown in FIG. 4, horizontal upper and lower ways which are ground and hardened are detachably mounted to a vertical surface of column 12, each by a plurality of bolts 50. The ways are vertically spaced apart and horizontally offset with respect to each other. The upper way 51 has an inclined upper surface 52 which slidably supports slide 13 thereon. The lower way 53 is rectangular in cross section, though tapered along its length, as shown in FIG. 6. Disposed between surface 54 of hob slide 13 and the bottom surface of way 52 is a gib 55 having a plurality of cylinders 56, all of which are in communication with a duct or conduit 57 defined along the length of gib 55. Disposed in each cylinder is a piston 58. Surface 54 of slide 13 and the bottom surface of gib 55 are complementarily tapered to permit adjustment of gib 55. When hydraulic fluid under pressure is forced into passage 57, pressure is exerted on the underside of pistons 58 and the pistons are forced against the underside of way 51. The pistons then act upon column 12 to which way 51 is rigidly attached. A reactive force is produced by the tapered under-surface of gib 55 acting on surface 54 which exerts a downward force on hob slide 13 and tends to pull hob slide 13 downwardly on sliding surface 52 of way 51. Surface 52 of way 51 reacts against the hob slide in both horizontal and vertical components and rigidly clamps hob slide 13 to column 12. Disposed between way 53 and surface 60 thereof, and slide 13 and surface 61 thereof, is a second gib 62 having a plurality of cylinders 63 defined therein (only two shown) and uniformly spaced along the length thereof. A duct or conduit 64 provides communication between the cylinders and disposed within the cylinders 63 are pistons 65 directed toward surface 61 of hob slide 13. When hydraulic fluid under pressure is introduced into duct 64 the pistons are moved to the right as viewed in FIGS. 5 and 6, tending to push hob slide 13 in that direction. This provides a clamping pressure along sliding surface 67 of slide 13 and surface 68 of way 53. The abutting surfaces of way 53 and gib 62, respectively, are formed on a complementary taper (FIG. 6) to permit adjustment of gib 62.

Slide 13 is primarily supported on dovetail way 51 and moves primarily on surf-ace 52 thereof. Way 53 and primarily surface 68 thereof merely acts as a guide as does the gib along surface 61 thereof during horizontal movement of slide 13.

With the construction disclosed, hob slide 13 is thus clamped to column 12 vertically along surface 52 of way 51 and further clamped to column 12 along surface 68 of way 53. Hob slide 13 has a downward locking force exerted thereon and a horizontal locking force which acts to the right as viewed in FIG. 5. These two forces are substantially equally distributed along the length of gib 62 and effectively make the hob slide a rigid portion of column 12. Hydraulic clamping pressure may be applied to gibs 55 and 62 in any suitable manner. FIG. 7 typifies a hydraulic system which may be utilized to apply fiuid under pressure to the gibs. Hydraulic fluid may be drawn from a source 70 by a pump 71, bypassed by a pressure relief valve 72. The fluid is applied through a pressure regulating valve 73 and a valve 74 operated by a solenoid 75 to a hydraulic intensifier 76. Intensifier 76 then applies the fluid under high pressure to gibs 55 and 62 (shown in broken line in FIG. 7). The position of gibs 55 and 62 may be longitudinally adjusted with respect to their ways by means of adjusting screws 77 and 78, respectively.

This construction produces a very rigid hobbing machine in which the major movable parts, namely, the hob slide and the work table are made rigid with respect to column 12 and such parts have zero clearance when the hob head is operated, thereby reacting all forces due to the hob cutting into the workpiece back to the massive rigid column 12. This increases the inherent accuracy of the hobbing operation, and conversely, decreases errors due to clearance between the movable parts which would be presented during a cutting operation by a hob.

In operation, a workpiece is placed in chuck 16 and engaged by footstock 25 and worktable 15 is moved to the desired position by means of lead screw 17. The hob is driven by a splined shaft 80 from a pulley 81 driven by a motor 82. The slide 13 may be driven by a hydraulic motor or other suitable means (not shown) and shaft 80 is longitudinally movable in the splined hub of bevel gear 83 and in meshing engamement with bevel gear 84 within the hob head housing 14.

From the foregoing it is seen that the object of the invention set forth above as well as those made apparent from the preceding disclosure are efficiently attained. Inasmuch as the invention may appear in various embodiments and modifications to the disclosed embodiments thereof, the appended claims are intended to cover all embodiments and modifications of the disclosed embodiments of the invention which do not depart from the spirit and scope thereof.

What is claimed is:

1. A hobbing machine comprising a vertical column providing vertical surfaces on one side thereof, upper and lower ways rigidly secured to said surfaces, a hob slide mounted on said ways for sliding movement thereon with respect to said one side of said column, a hob head carried on said slide, first and second gibs, each of said gibs being interposed between a surface of one of said ways and a facing surface on said slide, hydraulic means carried by each of said gibs arranged to produce a distributed force on said slide at said facing surfaces and react against the surface of each of said ways to urge said slide against normal sliding surfaces on said ways and produce a clamping force therebetween to rigidly lock said slide to said column through said Ways, a pair of spaced apart vertically extending guide rod carried by said column and having axes residing in a common vertical plane, a workhead including a spindle and a footstock coaxial with said spindle arranged to mount a workpiece for operation thereon by said hob head, first and second pairs of vertically aligned spaced apart bores defined in said workhead and adapted to receive said rods therein, anti-friction bearing means carried in said bores and disposed about said rods, and means for adjusting the clearance between said bearings and said rods.

2. A hobbing machine comprising a vertical column, a hob head slidably mounted to said column and having a hob arranged to operate upon a workpiece, a pair of spaced apart vertically extending guide rods carried by said column and having axes residing in a common vertical plane, a workhead including a spindle and a footstock coaxial with said spindle arranged to mount a workpiece for operation thereon by the hob, first and second pairs of vertically aligned spaced apart bores defined in said workhead and adapted to receive said rods therein, anti-friction bearing means carried in said bores and disposed about said rods, and means for adjusting the clearance between said bearings and said rods.

3. A hobbing machine comprising a vertical column, a pair of spaced apart vertically extending guide rods carried by said column and having axes residing in a common vertical plane, a workhead, first and second pairs of vertically aligned spaced apart bores defined in said workhead and adapted to receive said rods therein, anti-friction bearing means carried in said bores and disposed about said rods, and means for adjusting the clearance between said bearings and said rods.

4. A hobbing machine comprising a vertical column, a hob head slidably mounted to said column and having a hob arranged to operate upon a workpiece, a pair of spaced apart vertically extending cylindrical guide rods carried by said column and having axes residing in a common vertical plane, a workhead, said workhead having wall means defining first and second pairs of vertically spaced apart coaxial bores arranged to receive said rods therein, and anti-friction bearing means carried in said bores and disposed about said rods.

5. A hobbing machine comprising a vertical column, a hob head slidably mounted to said column and having a hob arranged to operate upon a workpiece, a pair of spaced apart vertically extending cylindrical guide rods carried by said column and having axes residing in a common vertical plane, a workhead, said workhead having wall means defining first and second pairs of vertically spaced apart coaxial bores arranged to receive said rods therein, anti-friction bearing means carried in said bores and disposed about said rods, and means for adjusting the clearance between said bearings and said rods.

6. The hobbing machine of claim 5 wherein said wall means are interrupted, and tightening means extending into said wall means through said interruption to provide adjustment of said clearance.

7. In combination, a supporting member, a movable member, a way rigidly secured to said supporting member, said movable member being slidably mounted on one surface of said way, said movable member and said way having spaced apart facing surfaces, clamping means disposed between said facing surfaces along the length thereof, constructed and arranged to produce a longitudinally distributed force on the said facing surface of said movable member which is reacted by said way at said facing surface thereof and said movable member is pulled against said one surface.

8. In combination, a supporting member, a movable member, first and second ways rigidly secured to said supporting member, said movable member being slidably mounted on said ways, said movable member and each of said ways having first and second pairs of spaced apart facing surfaces, first and second gibs disposed between said facing surfaces, hydraulic means carried by each of said gibs constructed and arranged to produce a longitudinally distributed force on the said facing surfaces of said movable member which is reacted by said ways at said facing surfaces thereof and said movable member is pulled against said ways on surfaces opposite the facing surfaces thereof.

9. In combination, a supporting member, a movable member, a way rigidly secured to said supporting member, said movable member being slidably mounted on one surface of said way, said movable member and said way having spaced apart facing surfaces, a gib disposed be tween said facing surfaces, hydraulic means carried by said gib constructed and arranged to produce a longitudinally distributed force on the said facing surface of said movable member which is reacted by said way at said facing surface thereof and said movable member is pulled against said one surface.

10. The arrangement of claim 9 wherein one of said facing surfaces is tapered along the length thereof and said gib is provided with a complementary taper along the length thereof, and means for adjusting the longitudinal position of said gib between said facing surfaces.

11. The arrangement of claim 9 wherein said gib has a plurality of cylinders defined therein along the length thereof, piston in said cylinders, a duct defined in said gib providing communication between said cylinders, and means for introducing fluid under pressure into said duct and cylinders to urge said pistons against one of said facing surfaces.

12. A hobbing machine comprising a vertical column providing vertical surfaces on one side thereof, upper and lower ways rigidly secured to said surfaces, a hob slide mounted on said ways for sliding movement thereon with respect to said one side of said column, first and second gibs, each of said gibs being interposed between a surface of one of said ways and a facing surface on said slide, said gibs being in adjustably fixed relation to said slides, hydraulic means carried by each of said gibs arranged to produce a longitudinally distributed force on said slide at said facing surfaces and react against the surface of each of said ways to urge said slide against normal sliding surfaces on said ways and produce a clamping force therebetween to rigidly lock said slide to said column through said ways.

13. A hobbing machine comprising a vertical column providing vertical surfaces on one side thereof, upper and lower ways rigidly secured to said surfaces, a hob slide mounted on said ways for sliding movement thereon with respect to said one side of said column, first and second gibs, each of said gibs being interposed between a surface of one of said ways and a facing surface on said slide, hydraulic means carried by each of said gibs arranged to produce a distributed force on said slide at said facing surfaces and react against the surfaces of each of said ways to urge said slide against normal sliding surfaces on said ways and produce a clamping force therebetween to rigidly lock said slide to said column through said Ways.

14. A hobbing machine comprising a base, a vertical column having parallel vertical surfaces on one side thereof extending from said base, first and second ways rigidly secured to said surfaces and providing sliding surfaces, a hob slide mounted to said ways for sliding movement on said surfaces, and a longitudinally extending expandable clamping means interposed between each of said ways and said slide constructed and arranged to react against said ways and act upon said slide so as to urge said slide into clamping engagement with the sliding surfaces of said ways.

15. The hobbing machine of claim 14 wherein the upper way has an upper surface defining an included acute angle with said column, and said slide is slidingly supported thereon, the opposite surface of said upper way providing a facing surface and said clam-ping means upon actuation thereof forces said slide against said upper surface.

16. A hobbing machine comprising a base, a vertical column having parallel vertical surfaces on one side thereof extending from said base, first and second ways rigidly secured to said surfaces and providing sliding surfaces, a hob slide mounted to said ways for sliding movernent on said surfaces, and a longitudinally extending expandable clamping means interposed between each of said ways and said slide constructed and arranged to react against said ways and act upon said slide so as to urge said slide into clamping engagement with the sliding surfaces of said ways, said sliding surface residing in transverse planes and being horizontally and vertically spaced apart.

No references cited.

WILLIAM W. DYER, 1a., Primary Examiner.

G. A. DOST, Assistant Examiner. 

1. A HOBBING MACHINE COMPRISING A VERTICAL COLUMN PROVIDING VERTICAL SURFACES ON ONE SIDE THEREOF, UPPER AND LOWER WAYS RIGIDLY SECURED TO SAID SURFACES, A HOB SLIDE MOUNTED ON SAID WAYS FOR SLIDING MOVEMENT THEREON WITH RESPECT TO SAID ONE SIDE OF SAID COLUMN, A HOB HEAD CARRIED ON SAID SLIDE, FIRST AND SECOND GIBS, EACH OF SAID GIBS BEING INTERPOSED BETWEEN A SURFACE OF ONE OF SAID WAYS AND A FACING SURFACE ON SAID SLIDE, HYDRAULIC MEANS CARRIED BY EACH OF SAID GIBS ARRANGED TO PRODUCE A DISTRIBUTED FORCE ON SAID SLIDE AT SAID FACING SURFACES AND REACT AGAINST THE SURFACE OF EACH OF SAID WAYS TO URGE SAID SLIDE AGAINST NORMAL SLIDING SURFACES ON SAID WAYS AND PRODUCE A CLAMPING FORCE THEREBETWEEN TO RIGIDLY LOCK SAID SLIDE TO SAID COLUMN THROUGH SAID WAYS, A PAIR OF SPACED APART VERTICALLY EXTENDING GUIDE RODS CARRIED BY SAID COLUMN AND HAVING AXES RESIDING IN A COMMON VERTICAL PLANE, A WORKHEAD INCLUDING A SPINDLE AND A FOOTSTOCK COAXIAL WITH SAID SPINDLE ARRANGED TO MOUNT A WORK- 